Around 300 lifeguards went on strike Tuesday forcing the closure of at least two public beaches, and the partial opening of several swimming complexes around the territory.
The lifeguards are angry over manpower shortages, saying it's created heavy a workload and safety concerns.
They say the problem has been exacerbated recently by a big influx of mainland swimmers.
Members of the Hong Kong and Kowloon Lifeguards' Union took their grievances to the Leisure and Cultural Services Department - which runs the pools and public beaches - by staging a three-hour sit-in outside its headquarters in Shatin.
The vice-chairman of the union, Alex Kwok, said the management must offer decent wages to attract people to work as lifeguards.
He said the salary of lifeguards is around HK$13,000.
"It's too low compared to the wages of ambulancemen and firemen which are over HK$17,000 a month," he said.
"Because of this many people preferred to be other civil servants than to be a lifeguard," Kwok added.
The LCSD said Butterfly Beach in Tuen Mun, and the Anglers' Beach in Tsuen Wan were suspended Tuesday until further notice because of insufficient lifeguards.
Red flags were hoisted, and the department urged the public not swim at these beaches for their own safety.
However, Kwok said they know the Silverstrand beach in Saikung was also closed because of the strike.
The industrial action also affected a number of public swimming complexes around the territory.
The Sham Shui Po Park Swimming Pool was temporarily closed until further notice, and several other venues were partially opened because of insufficient lifeguards. --RTHK